The present invention relates to semiconductor power devices, and more particularly to lateral power devices with self-biasing electrodes integrated therein. FIG. 1 shows a cross section view of a conventional lateral MOSFET 100. A lightly doped N-type drift region 104 extends over a highly doped N-type region 102. A P-type body region 106 and a highly dope N-type drain region 114 separated from each other by a laterally-extending N-type lightly doped drain (LDD) region are all formed in drift region 104. Highly doped N-type source region 110 is formed in body region 106, and heavy body region 108 is formed in body region 106. A gate 118 extends over a surface of body region 106 and overlaps source region 110 and LDD region 112. Gate 118 is insulated from its underlying regions by a gate insulator 116. The portion of body region 106 directly beneath gate 118 forms the MOSFET channel region 120.
During operation, when MOSFET 100 is biased in the on state, current flows laterally from source region 110 to drain region 114 through channel region 120 and LDD region 112. As with most conventional MOSFETs, performance improvements of lateral MOSFET 100 is limited by the competing goals of achieving higher blocking capability and lower on-resistance (Rdson). While LDD region 112 results in improved Rdson, this improvement is limited by the blocking capability of the transistor. For example, the doping concentration of LDD region 112 and the depth to which it can be extended are both severely limited by the transistor breakdown voltage.
These impediments to performance improvements are also present in other types of lateral power devices such as lateral IGBTs, lateral pn diodes, and lateral Schottky diodes. Thus, there is a need for a technique whereby the blocking capability, the on-resistance, as well as other performance parameters of various types of lateral power devices can be improved.